While out riding today I heard an on-and-off squeaking from down in the drive train of my road bike. It was a sound I never heard before. It was only when in the middle and smallest chain rings. When I got home, I found the squeaking to be coming form one of the jockey wheels (pulleys), not sure which one. I took of the chain and cleaned the whole drive train throroughly and then relubed, but the squeak is still there. Any ideas as to what's causing this and what I should do to fix it?
I've been caught in about 3 heavy downpours in the last few weeks and the roads around here are very gritty at the moment. So those are the conditions under which this sqeak developed. BTW, these are comparatively new Ultegra jocky wheels--I changed them about 3,000 miles ago.